1. Field
One embodiment of the invention relates to an information processor that supplies power through a universal serial bus while the information processor is off.
2. Description of the Related Art
Recently, a universal serial bus (USB: Registered Trademark) is becoming popular, and it has become possible to connect various electronic devices to an information processor, such as a personal computer (PC), through the USB. Such electronic devices (USB devices) include, for example, a keyboard, a mouse, a portable music player having a built-in battery configured to be charged by the PC, and the like.
Alongside with the widespread of the electronic device having the built-in battery, there is recently known a PC that can charge the USB device not only during the time when the power of the PC is on but also during the time when the power thereof is off. For example, Japanese Registered Utility Model No. 3127705 discloses such PC that switches between a circuit module and a power supply module depending on whether the PC is on or off, so that even when the PC is off, the power supply module of the PC can supply the power to the USB device.
Different types of recent USB devices often employ different settings in order to be charged through the USB. In particular, for example, there is known a USB device that employs a setting so that the USB device is charged through a power supply line only when a predetermined first voltage is applied to a data signal line. Further, there is known a USB device that employs a setting so that the USB device is charged through a power supply line only when a predetermined second voltage differing from the first voltage is applied to a data signal line. Still further, there is known a USB device that employs a setting so that the USB device is charged through a power supply line independently of a voltage supplied to a data signal line. Therefore, in order to charge each of the USB devices employing the aforementioned various settings (hereinafter, referred to as USB charging mode) while in the off state, a recent PC is configured to be able to select a USB charging mode that enables the USB device connected thereto to be charged, through an operating system (OS) utility of the PC.
However, conventionally, the USB charging mode employed to charge the USB device when the PC is off is selected through the OS utility while the OS is in operation. Hence, it is necessary to confirm whether the USB device connected to the PC can be charged in the selected USB charging mode, by turning off the PC power. As a result, it is necessary to turn the PC power off every time when the USB charging mode is tested, which causes the user's inconvenience.